enable video capture to support sharing across multiple renderer processes

media/video/capture/win/video_capture_device_win.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/video/capture/win/video_capture_device_win.h"
 
 #include <algorithm>
 #include <list>
 
 #include "base/string_util.h"
@@ skipping 315 matching lines @@
 
 void VideoCaptureDeviceWin::Allocate(
     int width,
     int height,
     int frame_rate,
     VideoCaptureDevice::EventHandler* observer) {
   if (state_ != kIdle)
     return;
 
   observer_ = observer;
+  observer_->OnDeviceState(true);
+
   // Get the camera capability that best match the requested resolution.
   const int capability_index = GetBestMatchedCapability(width, height,
                                                         frame_rate);
   Capability capability = capabilities_[capability_index];
 
   // Reduce the frame rate if the requested frame rate is lower
   // than the capability.
   if (capability.frame_rate > frame_rate)
     capability.frame_rate = frame_rate;
 
@@ skipping 113 matching lines @@
   if (mjpg_filter_) {
     graph_builder_->Disconnect(input_mjpg_pin_);
     graph_builder_->Disconnect(output_mjpg_pin_);
   }
 
   if (FAILED(hr)) {
     SetErrorState("Failed to Stop the Capture device");
     return;
   }
 
+  observer_->OnDeviceState(false);
   state_ = kIdle;
 }
 
 const VideoCaptureDevice::Name& VideoCaptureDeviceWin::device_name() {
   return device_name_;
 }
 
 // Implements SinkFilterObserver::SinkFilterObserver.
 void VideoCaptureDeviceWin::FrameReceived(const uint8* buffer,
                                           int length) {
@@ skipping 168 matching lines @@
   return diff_list.front().capability_index;
 }
 
 void VideoCaptureDeviceWin::SetErrorState(const char* reason) {
   DLOG(ERROR) << reason;
   state_ = kError;
   observer_->OnError();
 }
 
 }  // namespace media